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Venus Return Mission
Back to Venus Activities One of the most challenging problems in this game is to make a manned ship able to land on Venus and return home. In order to do so, a ship has to carry as much fuel as possible. There is no room for any error. The Ship The best way to complete this mission is to get the paid extension, which allows you to build larger ships. Additional solutions might include a backup ship, to push the main ship out of Earth's atmosphere or out of Earth's Sphere of Influence. The game has no pre-built ships and any player is free to build its own spacecraft. The ship listed on top-right of this article I named it Ana Express or simply AX (feel free to name it as you want in your game). It is a three-stage rocket with two double boosters on the third stage. It is ideal for return missions to Mercury, Mars and Venus. The first stage is made of seven big engines, with 140 t of fuel tanks. The second stage has two big engines free to use with the first stage, together with 35 t of fuel tanks. The other 5 engines, with their 100 t of fuel tanks, are used only after the first stage is detached. The third stage has two detachable double boosters, with a total of four small engines and 20 t of fuel. They also have two landing legs and two side parachutes. Because Venus has a dense atmosphere, there might be no need for landing legs. It is better to remove them, to avoid any extra weight. The central rocket of the second stage has a small engine, 10 t of fuel, a Capsule and a parachute. Liftoff The mission requires that all flight maneuvers are done nearly perfect, with no lost fuel. At launch, all seven engines of the first stage and the two separate engines of the second stage must be turned on, working at 100%. Up to 4000-5000 meters, where the atmosphere is denser, the ship must fly vertical, to pass faster. After this, the ship must gradually turn aside. Above 10 km, Earth's atmosphere is rarefied and will not cause significant problems. The first stage needs to be separated when it runs out of fuel, then it will fall back on Earth. Earth Orbit The second stage will carry the used two engines and their fuel tanks. Because of the limited building space, there is no other way. While using the second stage, the ship has to change angle, to gain low Earth orbit. In order to save as much fuel as possible, this must be done smoothly. Flight path must not get too far from the Kerman Line. After gaining orbit, some correction maneuvers must be done, to get an orbit as circular as possible. If everything is done perfectly, the second stage must still have little fuel left. Cruise To Venus After gaining low Earth orbit, the player must then select Venus, wait for a launch window and go for it. Accelerate the ship while it is close to Earth, to take benefit of the Oberth effect. Set the ship to a collision trajectory with Venus, directly from Earth. It is very important to save as much fuel as possible during this phase. Use the fuel left in the second stage (whatever is left, there is not much anyway). Then, use all the four engines of the boosters on the third stage in the same time. Take advantage of the Oberth effect. Take a burn only when your ship is in the best position. If this is not enough, take a second Oberth maneuver. It is possible to conduct even a third Oberth maneuver, but to do this, you must start immediately or slightly before Earth gets in the flight window towards Venus. Important: Because of gravitational perturbations from the Moon, the flight path is fluctuating. If you want to be sure your ship will reach target, check the trajectory after leaving Earth. Fire the engine forward or backward if you want to adjust trajectory. Advanced Flyby Technique One or two Moon gravity assists can send a ship out of Earth's sphere of influence. However, this requires for the game to last much longer. Using the Moon might send the ship on a heliocentric trajectory closer or further from Earth orbit. The player has to analyze where the Moon is and where the ship should go. Once in heliocentric orbit, the ship can take advantage of one or two Earth flybys. The idea is to lower the perihelion towards Venus orbit. This requires patience. Fix the Earth as target and wait until Earth will be very close to the ship. Then, fire the engines forward or backward, to intersect the Earth. Once the perihelion is close to Venus orbit, fire the engines backwards when you are at aphelion, to intersect Venus orbit. A good idea is to fire the engines forward when reaching perihelion, to avoid intersecting back the Earth. Then, wait until the ship will pass very close to Venus. When this happens, at aphelion, fire the engines forward or backward, to gain a crash trajectory with Venus. No matter what you do, it is important that, once you reach Venus, the fuel tanks in the boosters must be 2/3 full. If not, the mission is a failure. Venus Landing Venus has a very dense atmosphere. So, it can slow down any ship approaching. Just plunge into Venus nearly at any angle. Only if the flight trajectory merely touches the atmosphere, you are at risk of leaving Venus. But even so, the ship can be slowed just enough to reach Venus orbit. The second time when it will 'touch' the atmosphere, it will be slowed enough to land. The ship will be slowed down. Finally, when it falls below 2500 m, it can open the parachutes. Use the two side parachutes for this. Parachutes are enough to slow down a ship. However, if you land on rugged terrain, the impact might destroy one side engine of the boosters. Check out ground topography and use one small engine burn just before touchdown. To Venus Orbit This is the most challenging part of all and anything must be done perfectly in order to escape from Venus. At first, all the four engines of the boosters must be turned on at 100%. The ship must be turned towards a vertical ascending path, to pass the dense atmosphere with as little friction as possible. friction with the atmosphere will result in a significant fuel loss. This can be limited if speed is reduced. Keep speed between 40 and 50 m/s until you reach 10 km high. Also, keep a vertical path all the way to that altitude. Above 10 km high, Venus has an atmospheric density that can allow ships to pierce through much faster. Increase engine thrust to 100% and start tilting the trajectory. Do this gradually, with the desire to reach Venus orbit just above the atmosphere. At some point, while still inside the atmosphere, boosters will run out of fuel. Detach both of them fast. If this is not done fast enough, the ship will start running in circles. Then, turn on the engine. If everything is done correctly, the ship will reach low Venus orbit with about 1/2 fuel left. Cruise Back If the ship still has 2/3 fuel left, it should be able to return to Earth. Select Earth as target and take advantage of two Oberth maneuvers. Set the ship on a crash trajectory with Earth (see details below). Rescue Operations There is a high chance that a ship will not have enough fuel to return to Earth. In this case, there are a few alternative solutions: *Send a backup ship, to push the main ship out of Venus sphere of influence. *Use your fuel (but not all) to escape Venus sphere of influence. Then, wait for a planetary alignment for a gravity assist from Venus. This can rise your aphelion to intersect the Earth. Ideal is to send the ship on an Earth impact trajectory. Earth Landing Earth has a dense atmosphere, but not dense enough for a direct impact. Try to hit the atmosphere in an angle. Set the flight path so that the ship should touch the surface but not fly towards the core of Earth. The ship should reach Earth with only very little fuel left. The atmosphere will slow down the ship just enough to open parachute. Important: If the flight path is set towards Earth's center, the atmosphere might not slow the ship enough. Sometimes, the impact with Earth's surface might cause destruction of one engine. When landing on mountains, the ship might suffer from an impact and turn over, destroying the capsule. To avoid dangers, it is good to still have some fuel left for a small engine burn two seconds before touchdown. Friction Problem Very important for Venus missions is that the dense atmosphere slows down any ship that is not aerodynamic. In the image to the left (middle), there is a large, three-stage Venus Launch Vehicle, built with the paid extension. It has multiple side parachutes and RCS thrusters. On top, it has a third stage, with Ion Engines, a battery, a docking port and two solar panels. In order to launch such a big vehicle from Earth, you need a powerful ship build with large parts (left). Then, the ship needs to refuel. The first stage manages to reach to 7000 or 8000 km high, while the boosters on the second stage brings the rocket to space. The central rocket of the second stage should be enough to gain Venus orbit. The third stage uses its ion engines to bring the capsule back home. One can note that, to bring an object that is not aerodynamic back to Earth, far more fuel is needed. Because of this, if you use ion engines, it is good to leave them in orbit around Venus to dock with them later. See Also *Venus *Venus Activities *What To Do In Spaceflight Simulator Category:Tutorial